To reduce dependence on imported oil, compact, affordable, highly efficient and durable compressor systems (mountable on walls) are needed for compressing home-line natural gas from nearly 1 atmosphere (14.7 psi) to more than 3500 psi in order to achieve high enough energy density for a reasonable driving range. Natural gas is very abundant in the US and significantly cleaner to burn than other fossil fuels. More favorable residential gas rates (i.e., 50% cheaper than gasoline or diesel) make compressed natural gas (CNG) very attractive. US automakers have so far been very reluctant to make and sell CNG-powered cars due to technological and economic barriers. Of the 12.5 million global natural gas-powered vehicles, only about 120,000 are in the U.S. and most of these vehicles are used for public/school transportation, waste management, and smaller demonstration fleets operated by federal, state, and city governments. Natural gas currently accounts for ≈2% of total energy used for transportation in US.
One of the major technological barriers to overcome is to compress natural gas from home outlets to as much as 5,000 psi and then fill a vehicle's tanks every time quickly and safely for over 10,000 hours of operation. Current compressors with such high capacities are either very expensive and bulky or very difficult to install and operate cost-effectively for home-refueling applications. Existing compressor systems suffer from high-friction, wear, and tear of their sealing and sliding surfaces which rely on low-friction materials (such as Teflon) or coatings (diamond-like carbon films (DLC), MoS2) which fail in the long run and will not survive under the much harsher operating conditions of future compressors.
Therefore, there is an urgent need for a novel, low-cost, high-performance compressor technology suitable for home-refueling applications made possible through the design and development of a catalytically active nanocomposite coating that in turn extract self-replenishing (or -healing), superlubricious carbon film directly from the natural gas or hydrocarbon gas itself and subsequently deposited on sealing and sliding surfaces.